This invention relates to stabilization of polyolefins. In one of its aspects this invention relates to the stabilization of pigmented polyolefins. In another of its aspects this invention relates to ultraviolet stabilazation of pigmented polyolefin. In still another aspect of this invention it relates to stabilizer systems for polymers of propylene.
In one of its concepts this invention relates to a multi-component additive system which provides stabilization against ultraviolet deterioration for homopolymers of propylene and copolymers of propylene and another aliphatic 1-olefin containing 2-8 carbon atoms in which the comonomer constitutes up to about 20 mol percent of the copolymer.
It has been well known in the art that pigmented polyolefins, particularly polymers of propylene, can be stabilized against ultraviolet deterioration using nickel-base stabilizing compositions. These stabilizers have proved effective, but they are expensive and in some applications a green color is imparted to the resin which must be masked using other pigments. Considerable effort has, therefore, been expended to develop pigmented polymers of propylene which are readily melt spun into fibers and which possess sufficient stability to ultraviolet light and oxidative degradation with the use of ultraviolet stabilizers other than nickel-base compounds.
It is therefore an object of this invention to provide an ultraviolet stabilizer system for pigmented polyolefins. It is also an object of this invention to provide a stabilized pigmented polyolefin composition, especially a stabilized composition comprising a polymer of propylene. It is still another object of this invention to provide a method for stabilizing a pigmented polyolefin, particularly a polymer of propylene.
Other objects, aspects, and the various advantages of this invention will become apparent upon reading this specification and the appended claims.